# How many microstates are defined to exist at absolute zero for a perfect crystal?

##### 1 Answer

Jun 6, 2017

The third law of thermodynamics states that in that case, the absolute entropy becomes zero for a perfect crystal:

#S = 0# at#T = "0 K"# .

Statistically, from Boltzmann's theorem,

#S = 0 implies ln W = 0# where

#W# is the number of microstates occupied.

Thus,

However, quantum fluctuations make it difficult that such a state becomes localised because the fluctuations occurring are non-negligible compared to the energy available.

This has an important implication - absolute zero is difficult to maintain.